U.S. patent number 10,216,136 [Application Number 15/641,533] was granted by the patent office on 2019-02-26 for image forming apparatus.
This patent grant is currently assigned to Canon Kabushiki Kaisha. The grantee listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Takuya Matsumura, Takayuki Suzuki, Nobuhiro Tani.
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United States Patent |
10,216,136 |
Suzuki , et al. |
February 26, 2019 |
Image forming apparatus
Abstract
An image forming apparatus includes an apparatus body, a movable
unit relatively movable between a first position and a second
position, a lock portion configured to lock the movable unit to the
apparatus body and an urging portion. The lock portion includes a
locked member provided on one of the movable unit and the apparatus
body, and a locking member provided on the other of the movable
unit and the apparatus body and configured to move between a lock
position and a retracting position. The urging portion is
configured to urge the movable unit located at a position between
the first position and the second position, toward the first
position. The position between the first position and the second
position is a position at which the locking member in the lock
position and the locked member contact each other.
Inventors: |
Suzuki; Takayuki (Kashiwa,
JP), Matsumura; Takuya (Kashiwa, JP), Tani;
Nobuhiro (Shiki, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
N/A |
JP |
|
|
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
|
Family
ID: |
60940572 |
Appl.
No.: |
15/641,533 |
Filed: |
July 5, 2017 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20180017935 A1 |
Jan 18, 2018 |
|
Foreign Application Priority Data
|
|
|
|
|
Jul 12, 2016 [JP] |
|
|
2016-137495 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03G
21/1633 (20130101); G03G 21/1638 (20130101); G03G
21/1842 (20130101); B41J 11/006 (20130101); G03G
15/70 (20130101); G03G 2221/1654 (20130101) |
Current International
Class: |
G03G
21/16 (20060101); G03G 21/18 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
H10-063163 |
|
Mar 1998 |
|
JP |
|
H11-106093 |
|
Apr 1999 |
|
JP |
|
2000-147850 |
|
May 2000 |
|
JP |
|
Primary Examiner: Therrien; Carla J
Attorney, Agent or Firm: Venable LLP
Claims
What is claimed is:
1. An image forming apparatus comprising: an apparatus body; a
movable unit relatively movable to the apparatus body between a
first position at which the movable unit is positioned when an
image is formed and a second position which is away from the first
position; a lock portion configured to lock the movable unit to the
apparatus body, the lock portion comprising: a locked member
provided on one of the movable unit and the apparatus body; and a
locking member provided on the other of the movable unit and the
apparatus body and configured to move between a lock position and a
retracting position, the lock position being a position at which
the locking member engages with the locked member to lock the
movable unit, the retracting position being a position to which the
locking member is retracted from the lock position; an urging
portion configured to urge the movable unit located at a position
between the first position and the second position, toward the
first position, the position between the first position and the
second position being a position at which the locking member in the
lock position and the locked member contact each other; a catch
unit comprising a first catch portion provided on the movable unit
and a second catch portion provided on the apparatus body, the
catch unit being configured such that the second catch portion
holds the first catch portion to hold the movable unit not to
release the movable unit from the apparatus body and releases the
first catch portion in response to a movement of the movable unit
from the first position toward the second position, wherein the
first catch portion comprises a held member that is held by the
second catch portion and supported such that the held member can
move relative to the movable unit, and the urging portion comprises
an elastic member arranged between the held member and the movable
unit.
2. The image forming apparatus according to claim 1, wherein the
second catch portion comprises a held member that engages with the
first catch portion and is supported such that the held member can
move relative to the apparatus body, and the urging portion
comprises an elastic member arranged between the held member and
the apparatus body.
3. The image forming apparatus according to claim 1, wherein the
urging portion is arranged between the held member and the movable
unit such that, in a state where the held member is held by the
second catch portion, urging force of the elastic member increases
as the movable unit moves toward the second position.
4. The image forming apparatus according to claim 1, wherein at
least one of the held member and the second catch portion comprises
a magnet.
5. The image forming apparatus according to claim 4, wherein the
urging portion has a maximum urging force smaller than a sticking
force of the magnet.
6. The image forming apparatus according to claim 1, wherein the
urging portion comprises an elastic member arranged between the
movable unit and the apparatus body.
7. The image forming apparatus according to claim 1, wherein the
locking member moves from the lock position to the retracting
position with the aid of a self-weight of the locking member.
8. The image forming apparatus according to claim 7, wherein the
locking member is supported such that the locking member can pivot
on a pivot supporting axis, and a weight balance of the locking
member is set such that a rotation moment of the locking member in
a direction in which the locking member pivots from the lock
position to the retracting position is larger than a rotation
moment of the locking member in a direction in which the locking
member pivots from the retracting position to the lock
position.
9. The image forming apparatus according to claim 1, wherein the
locking member is supported such that the locking member can pivot
on a pivot supporting axis and the locked member and the locking
member are positioned such that, when the movable unit is
positioned in a state where the locked member and the locking
member contact each other, a line passing through a contact point
between the locked member and the locking member and through the
pivot supporting axis is substantially parallel to a moving
direction of the movable unit.
10. The image forming apparatus according to claim 1, wherein the
lock portion comprises a solenoid used to move the locking
member.
11. The image forming apparatus according to claim 1, wherein the
movable unit comprises a door that covers a front face of the
apparatus body and can open and close.
12. The image forming apparatus according to claim 1, wherein the
movable unit comprises a drawing unit that can be drawn out from
the apparatus body.
13. The image forming apparatus according to claim 1, wherein the
locked member comprises a predetermined gap portion, and the
locking member moves into or out of the gap portion, and has an
engagement portion whose thickness in a moving direction of the
movable unit is smaller than a width of the gap portion.
14. An image forming apparatus comprising: an apparatus body; a
movable unit relatively movable to the apparatus body between a
first position at which the movable unit is positioned when an
image is formed and a second position which is away from the first
position; a lock portion configured to lock the movable unit to the
apparatus body, the lock portion comprising: a locked member
provided on one of the movable unit and the apparatus body; and a
locking member provided on the other of the movable unit and the
apparatus body and configured to move between a lock position and a
retracting position, the lock position being a position at which
the locking member engages with the locked member to lock the
movable unit, the retracting position being a position to which the
locking member is retracted from the lock position; and an urging
portion configured to urge the movable unit located at a position
between the first position and the second position, toward the
first position, the position between the first position and the
second position being a position at which the locking member in the
lock position and the locked member contact each other, wherein the
urging portion urges the movable unit, located at the position
between the first position and the second position, toward the
first position, the position being the position at which the
locking member located in the lock position and the locked member
contact each other, and wherein the locking member located in the
lock position and the locked member do not contact each other in a
state where the movable unit is located at the first position.
15. An image forming apparatus comprising: an apparatus body; a
movable unit relatively movable to the apparatus body between a
first position at which the movable unit is positioned when an
image is formed and a second position which is away from the first
position; a lock portion configured to lock the movable unit to the
apparatus body, the lock portion comprising: a locked member
provided on one of the movable unit and the apparatus body; and a
locking member provided on the other of the movable unit and the
apparatus body and configured to move between a lock position and a
retracting position, the lock position being a position at which
the locking member engages with the locked member to lock the
movable unit, the retracting position being a position to which the
locking member is retracted from the lock position; and an urging
portion configured to urge the movable unit located at a position
between the first position and the second position, toward the
first position, the position between the first position and the
second position being a position at which the locking member in the
lock position and the locked member contact each other, wherein the
locked member comprises a predetermined gap portion, wherein the
locking member moves into or out of the gap portion, and has an
engagement portion whose thickness in a moving direction of the
movable unit is smaller than a width of the gap portion, wherein
the locked member is a hook member that comprises the gap portion,
and wherein the gap portion is concave.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an image forming apparatus that
forms an image on a sheet.
Description of the Related Art
Generally, an image forming apparatus, such as a copying machine, a
printer, a facsimile, or a multifunction printer in which functions
of the foregoing machines are combined with each other, is provided
with a cover that can be freely opened and closed with respect to
an apparatus body of the image forming apparatus. One image forming
apparatus such as Japanese Patent Application Publication No.
2000-147850 includes a lock mechanism that locks the cover so that
the cover is not opened. The lock mechanism locks the cover because
opening the cover may lead to, for example, a failure of the image
forming apparatus or tear of a sheet that is stuck in the
apparatus. Locking the cover can prevent the failure of the
apparatus and the tear of the sheet.
The lock mechanism of Japanese Patent Application Publication No.
2000-147850 includes a stopper and a pivotable lock actuator
provided on the cover and locks the cover by the lock actuator
moving into a space between the stopper and the cover. Here, if a
user tries to open the cover in a state where the cover is locked
by the lock mechanism, the lock actuator and the stopper can be in
firm contact with each other, i.e. half-open state of the
cover.
As a result, a great frictional force is produced between the lock
actuator and the stopper and the motion of the lock actuator may be
disturbed by the frictional force. In particular, when the
frictional force is greater than a force used to move the lock
actuator, it may be difficult to change the lock mechanism from its
lock state to unlock state. Thus, the change into the unlock state
cannot be reliably performed.
SUMMARY OF THE INVENTION
According to an aspect of the present invention, an image forming
apparatus includes an apparatus body, a movable unit relatively
movable to the apparatus body between a first position at which the
movable unit is positioned when an image is formed and a second
position which is away from the first position, a lock portion
configured to lock the movable unit to the apparatus body and an
urging portion. The lock portion includes a locked member provided
on one of the movable unit and the apparatus body, and a locking
member provided on the other of the movable unit and the apparatus
body and configured to move between a lock position and a
retracting position. The lock position is a position at which the
locking member engages with the locked member to lock the movable
unit, and the retracting position is a position to which the
locking member is retracted from the lock position. The urging
portion is configured to urge the movable unit located at a
position between the first position and the second position, toward
the first position. The position between the first position and the
second position is a position at which the locking member in the
lock position and the locked member contact each other.
Further features of the present invention will become apparent from
the following description of exemplary embodiments with reference
to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic configuration diagram of a printer of an
embodiment of the present invention.
FIG. 2A is a diagram illustrating the printer of FIG. 1 in a state
where a front door of the printer is closed.
FIG. 2B is a diagram illustrating the printer of FIG. 1 in a state
where the front door is opened and a sheet conveyance unit is
drawn.
FIG. 3A is a diagram illustrating a lock unit in an unlock
state.
FIG. 3B is a diagram illustrating the lock unit in a lock
state.
FIG. 4 is a block diagram of a control portion.
FIG. 5 is a flowchart illustrating a control operation performed in
a jam handling.
FIG. 6A is a schematic diagram illustrating a lock mechanism in a
close state.
FIG. 6B is a schematic diagram illustrating the lock mechanism in a
half-open state.
DESCRIPTION OF THE EMBODIMENTS
Hereinafter, a printer 1 of the present embodiment, which serves as
the image forming apparatus, will be described. Here, note that
features of components of the below-described embodiments, such as
size, material, shape, and relative arrangement, should be changed
as necessary depending on a configuration and various conditions of
an apparatus to which the present invention is applied, and thus
are not intended to limit the scope of the present invention.
As shown in FIG. 1, the printer 1 includes a sheet feeding portion
10 that feeds a sheet, a sheet conveyance portion 20 that conveys
the sheet fed by the sheet feeding portion 10, and an image forming
portion 30 that forms an image on the sheet conveyed by the sheet
conveyance portion 20. The sheet feeding portion 10 includes a
plurality of (four in this embodiment) sheet cassettes 11a, 11b,
11c, and 11d in a lower portion of an apparatus body 2 of the
printer 1. Each of the sheet cassettes 11a, 11b, 11c, and 11d
storing sheets S is composed of a sheet supporting portion on which
the sheets S are supported (stacked). Each of the sheet cassettes
11a, 11b, 11c, and 11d is provided with an sheet supporting plate,
on which the sheets are supported (stacked). The sheet supporting
plate moves up and down so that a sheet height of the uppermost
sheet is kept at a predetermined sheet feeding position.
The sheet feeding portion 10 also includes separation feeding
portions 13a, 13b, 13c, and 13d, each of which separates and feeds
the stacked sheets one by one. Since the separation feeding
portions 13a, 13b, 13c, and 13d have substantially the same
configuration, the configuration of only the separation feeding
portion 13a will be described below, and the description of the
configuration of the separation feeding portions 13b, 13c, and 13d
will be omitted. The separation feeding portion 13a includes a
pickup roller 14a that contacts and feeds an uppermost sheet of the
stacked sheets on the sheet cassette 11a, a separation roller pair
15a disposed downstream in a sheet conveyance direction of the
pickup roller 14a, and a drawing roller pair 16a. The separation
roller pair 15a includes a conveyance roller 15a1 and a separation
roller 15a2. The conveyance roller 15a1 rotates in the same
direction as the pickup roller 14a. The separation roller 15a2 is
driven to rotate in a direction opposite to the sheet conveyance
direction, or is stopped from rotating, when two or more sheets are
fed at the same time. The conveyance roller 15a1 and the separation
roller 15a2 constitute a separation nip. Thus, the separation nip
separates a lower sheet that is fed along with an uppermost sheet,
from the uppermost sheet. The drawing roller pair 16a is disposed
downstream in the sheet conveyance direction of the separation
roller pair 15a, where the sheet conveyed from the separation
roller pair 15a is drawn out and conveyed toward a registration
roller pair 21 described later.
The sheet conveyance portion 20 includes a plurality of roller
pairs disposed downstream in the sheet conveyance direction of the
drawing roller pair 16a, and conveys the sheet toward a secondary
transfer portion 35. The above-described registration roller pair
21 is one roller pair among the plurality of roller pairs, located
upstream of the secondary transfer portion 35 and nearest to the
secondary transfer portion 35 that transfers an image onto the
sheet. The registration roller pair 21 conveys the sheet to the
secondary transfer portion 35 in synchronization with an image
formation of the image forming portion 30, and performs skew
correction of the sheet.
The image forming portion 30 includes process cartridges 31Y, 31M,
31C, and 31Bk for yellow, magenta, cyan, and black, exposing units
40Y, 40M, 40C, and 40Bk provided for the respective process
cartridges, and an intermediate transfer unit 50. The process
cartridges 31Y, 31M, 31C, and 31Bk are arranged along an
intermediate transfer belt 51 in the order of yellow, magenta,
cyan, and black. Since the process cartridges have substantially
the same configuration except the colors of toner contained, the
configuration of only the process cartridge 31Y for yellow will be
described below.
The process cartridge 31Y includes a photosensitive drum 32Y, a
charging unit 38Y, a developing unit 33Y, and a drum cleaning unit
34Y. The charging unit 38Y, the developing unit 33Y, and the drum
cleaning unit 34Y are arranged around the photosensitive drum 32Y.
The charging unit 38Y uniformly charges the surface of the
photosensitive drum 32Y so that all the surface has the uniform
electrical potential. The exposing unit 40Y emits a laser beam,
which is produced based on an image signal, to the uniformly
charged surface to form an electrostatic latent image on the
surface. The electrostatic latent image, formed on the surface of
the photosensitive drum 32Y, is developed by the developing unit
33Y to create a toner image.
The intermediate transfer unit 50 includes the intermediate
transfer belt 51, a driving roller 52, a tension roller 53, a
secondary transfer inner roller 54, and primary transfer rollers
55Y, 55M, 55C, and 55Bk. The intermediate transfer belt 51 is wound
around and stretched between these rollers. The primary transfer
rollers are arranged to face the above-mentioned yellow, magenta,
cyan and black photosensitive drums 32Y, 32M, 32C, and 32Bk with
the intermediate transfer belt 51 interposed, and form primary
transfer portions together with the photosensitive drums used for
the respective colors. Thus, each toner image of each color formed
on each photosensitive drum is transferred, in the primary transfer
portion, onto the intermediate transfer belt 51 such that one toner
image is superimposed on another toner image, so that a full-color
toner image is formed on the intermediate transfer belt 51. In the
present embodiment, the intermediate transfer belt 51 is driven by
the driving roller 52 in a direction indicated by an arrow B in
FIG. 1, and the toner images for the respective colors are
transferred onto the intermediate transfer belt 51 in the order of
yellow, magenta, cyan, and black.
The secondary transfer inner roller 54 is arranged downstream of
the primary transfer portion in a rotational direction of the
intermediate transfer belt 51, i.e. direction indicated by the
arrow B, and constitutes the secondary transfer portion 35 along
with a secondary transfer outer roller 56 arranged to face the
secondary transfer inner roller 54 with the intermediate transfer
belt 51 interposed. When the sheet is conveyed to the secondary
transfer portion 35 in synchronization with the conveyance of the
full-color toner image formed on the intermediate transfer belt 51,
a transfer bias is applied to the secondary transfer outer roller
56 to transfer the full-color toner image onto the sheet. Residual
toner on the intermediate transfer belt is removed by a belt
cleaning unit 57.
On the downstream side of the secondary transfer portion 35, a
pre-fixation conveyance unit 64 and a fixing unit 60 are provided.
The pre-fixation conveyance unit 64 conveys the sheet onto which an
unfixed-toner image is transferred. The fixing unit 60 is
configured to fix the unfixed-toner image onto the sheet. The
fixing unit 60 includes a heating roller 62 that contains a halogen
heater, and an opposing roller 63 that faces the heating roller 62.
The heating roller 62 and the opposing roller 63 constitute a
heating nip, which heats and pressurizes the unfixed-toner image
and fixes the unfixed-toner image onto the sheet.
The sheet, on which the toner image is fixed by the fixing unit 60
serving as a fixing portion, is conveyed by a sheet discharge
portion 70 and discharged to a sheet discharge tray 72 by a sheet
discharge roller pair 71. When duplex printing is performed, the
sheet is conveyed to a sheet-inversion conveyance unit 74 by a
path-branch conveyance unit 73, which is provided between the
fixing unit 60 and the sheet discharge roller pair 71. The sheet is
then conveyed to a duplex-printing conveyance path 87 by the
sheet-inversion conveyance unit 74, and conveyed to the secondary
transfer portion 35 again.
Sheet Conveyance Route
Next, a sheet conveyance route of the printer 1 will be described.
As shown in FIG. 1, the printer 1 has a sheet conveyance route in
the apparatus body 2. The sheet conveyance route includes a sheet
feeding path 81, a sheet conveyance path 82, an image forming path
83, a sheet discharge path 84, and a sheet-inversion conveyance
path 85. The sheet feeding path 81 extends in a vertical direction
in a right side portion (one side) of the apparatus body, and along
which the sheet fed by the separation feeding portions 13a, 13c,
and 13d are conveyed. The sheet conveyance path 82 is provided
downstream with respect to the sheet feeding path 81 in the sheet
conveyance direction, and is formed so that the sheet, which has
been conveyed along the sheet feeding path 81, is conveyed to the
secondary transfer portion 35 along the sheet conveyance path 82.
The image forming path is provided downstream with respect to the
sheet conveyance path 82 in the sheet conveyance direction, and is
formed so that an image forming process is performed in order to
form and fix a toner image on the sheet, which is present on the
image forming path 83.
The sheet discharge path 84 is provided downstream with respect to
the image forming path 83 in the sheet conveyance direction, and is
formed so that the sheet, on which the toner image is formed on the
image forming path 83, is discharged to the sheet discharge tray
72. The sheet-inversion conveyance path 85 includes a sheet
inversion path and a duplex-printing conveyance path 87. The sheet
inversion path 86 branches off the sheet discharge path 84 and
extends in a downward direction in a left side portion (the other
side) of the apparatus body. The duplex-printing conveyance path 87
conveys the sheet that is inverted in the sheet inversion path 86,
and back to the sheet conveyance path 82.
Since the sheet conveyance route is constituted by the plurality of
paths 81 to 87, as described above, the sheet can be stuck at any
spot of the plurality of paths and cause a sheet jam. As
countermeasures to this, as shown in FIGS. 2A and 2B, the printer 1
is configured as follows: the sheet cassettes 11a to 11d can be
drawn out, a front panel 90 is provided with an open-and-close door
90a, a left side-panel 91 is provided with an open-and-close door
91a, and a right side-panel 92 is provided with an open-and-close
door. In addition, the printer 1 is configured such that, when a
sheet jam occurs, an occurrence spot of the sheet jam can be
accessed through an appropriate route.
The sheet conveyance path 82, the image forming path 83, and the
duplex-printing conveyance path 87 constitute a sheet conveyance
unit 100, which is unitized and can be drawn out from the apparatus
body 2. Specifically, the sheet conveyance unit 100 includes the
fixing unit 60 and the pre-fixation conveyance unit 64, and has a
configuration in which guide components and conveyance rollers
(which constitute the sheet conveyance path 82, the image forming
path 83, and the duplex-printing conveyance path 87) are integrally
unitized.
Thus, when a sheet jam occurs in the sheet conveyance path 82, the
image forming path 83, and/or the duplex-printing conveyance path
87, the printer 1 of the present embodiment can resolve the sheet
jam as follows: first, the front door 90a of the front panel 90
that covers a front face of the apparatus body is opened; then, the
sheet conveyance unit 100 is drawn out from the apparatus body 2 to
remove the sheet. When a sheet is stuck in the separation feeding
portions 13a to 13d, each of the sheet cassettes 11a to 11d is
drawn out to remove the sheet, which is stuck in the separation
feeding portions. When a sheet jam occurs in the sheet feeding path
81, the open-and-close door (not shown) of the right side-panel 92
is opened to remove the sheet. When a sheet jam occurs in the sheet
inversion path 86, the open-and-close door 91a of the left
side-panel 91 is opened to remove the sheet.
Structure of Lock Unit
The printer 1 also includes a lock unit (lock portion) 110 that
locks the front door 90a so that the front door 90a is not opened
with respect to the apparatus body 2. As shown in FIGS. 3A and 3B,
the lock unit 110 includes a first lock portion 120 provided on the
front door 90a, and a second lock portion 130 provided on the
apparatus body 2. In the present embodiment, the first lock portion
120 is a holder 121 that includes a predetermined gap portion 122
and serves as a locked member. The second lock portion 130 is a
drive unit that includes a locking member 131 and a drive source
132. The locking member 131 has an engagement portion 131a that
moves into or out of the gap portion 122. The drive source 132
allows the engagement portion 131a to move into or out of the gap
portion 122 of the holder 121.
More specifically, the holder 121 is an electrogalvanized hook
member which is fixed on the front door 90a, and in which the gap
portion 122 is formed by a concave hook portion (concave portion)
121a. The opening of the hook portion 121a faces upward. The
locking member 131 is a plate-like member that is provided such
that the locking member 131 can pivot on a pivot supporting axis
(pivot shaft) 133 extending in a width direction perpendicular to a
moving direction of the front door 90a (i.e. front-rear direction
of the printer 1). An end portion of the locking member 131 on the
front door 90a side is bent toward the width direction, and serves
as the engagement portion (end portion) 131a that engages with the
hook portion 121a. In addition, the drive source 132 is attached to
the locking member 131 at an end portion 131b of the locking member
131 on a side opposite to the engagement portion side. The drive
source 132 is a solenoid that allows the locking member 131 to
pivot on the pivot supporting axis 133. When the solenoid 132 is
turned on or off in a state where the front door 90a is closed, an
iron core of the solenoid 132 moves up or down to pivot the locking
member 131, so that a lock state and an unlock state of the front
door 90a can be changed.
The locking member 131 is structured such that a portion of the
locking member 131 on the solenoid 132 side with respect to the
pivot shaft 133 weighs more than a portion of the locking member
131 on the engagement portion 131a side. In the present embodiment,
a weight ratio of the portion on the engagement portion 131a side,
with respect to the pivot shaft 133, to the portion on the solenoid
132 side is 1:1.4. With this, when the solenoid 132 is turned off,
the locking member 131 is subjected to a turning force by its own
weight, and pivots toward an X-direction indicated by an arrow in
FIG. 3A. Thus, the engagement portion 131a moves upward with
respect to the holder 121, causing the unlock state of the front
door 90a.
The lock unit 110 is arranged such that, in the lock state, a line
perpendicular to the engagement portion 131a of the locking member
131 and to the pivot shaft 133 is substantially parallel to the
moving direction of the front door 90a, i.e. direction in which the
hook moves.
Control in Jam Occurrence
Next, a control operation performed when a sheet jam occurs will be
described. As shown in FIG. 4, the printer 1 has a control portion
140. The control portion 140 includes a CPU 141 that serves as a
calculation portion, and a ROM 142 and a RAM 143 that serve as a
memory portion. Also, a plurality of sheet detection sensors 160
used to detect a sheet are provided along the above-described sheet
conveyance route. The plurality of sheet detection sensors 160 are
connected to the control portion 140 via a bus line 145.
As shown in FIG. 5, when the control portion 140 detects the
occurrence of a sheet jam, depending on a detection result by the
sheet detection sensors 160 (S1: Yes), the control portion 140
first determines an occurrence spot of the sheet jam (S2). That is,
the control portion 140 detects the position of a sheet that is
stuck in the apparatus body, by a certain sensor of the plurality
of sheet detection sensors 160 being detecting the sheet, and
determines the occurrence spot of the sheet jam.
Then, the control portion 140 determines whether to lock the front
door 90a, depending on the position of the sheet that is stuck in
the apparatus body (S3). That is, when the sheet is stuck across a
space between the sheet conveyance unit 100 and the apparatus body
2, the control portion 140 determines to lock the front door 90a.
In addition, when the occurrence spot of the sheet jam needs to be
accessed from another portion (such as the side panel or the sheet
cassette) other than the front door 90a, the control portion 140
also determines to lock the front door 90a. For example, the
control portion 140 determines to lock the front door 90a, when the
leading edge of the sheet reaches the sheet discharge tray 72 and
the trailing edge of the sheet remains upstream with respect to the
inner discharge roller 46, that is, when the sheet is stuck across
a space between the sheet conveyance unit 100, which serves as a
drawing unit, and the path-branch conveyance unit 73.
Also, when the control portion 140 determines that the occurrence
spot of the sheet jam is a spot for which the control portion 140
needs not to open the front door 90a for handling the sheet jam,
the control portion 140 turns the solenoid 132 ON to lock the front
door 90a (S4). Then, the control portion 140 displays a message on
a panel portion 151 of an operation portion 150, instructing a user
to open the open-and-close door 91a of the left side panel 91 or
the open-and-close door of the right side panel 92 or to draw the
sheet cassettes 11a to 11d and to resolve the sheet jam.
On the other hand, when the control portion 140 determines that the
occurrence spot of the sheet jam is a spot for which the control
portion 140 needs to open the front door 90a for handling the sheet
jam (S3: No), the control portion 140 keeps the solenoid 132 OFF.
Then, the control portion 140 displays a message, instructing a
user to open the front door 90a and to resolve the sheet jam, on
the panel portion 151 of the operation portion 150.
After that, when a user follows the instruction to perform the
jam-handling operation, and when the control portion 140 detects
that the sheet jam is resolved (S5 Yes), the control portion 140
controls the lock unit 110 to unlock the front door 90a (S6). Thus,
when a sheet is stuck across a space between the sheet conveyance
unit 100 and the apparatus body 2 and causes a sheet jam, the front
door 90a is locked to prevent wrong operation performed by a user,
and to prevent the sheet conveyance unit 100 from being drawn out,
preventing a sheet from being torn.
Lock Mechanism of Front Door
Next, with reference to FIGS. 6A and 6B, a lock mechanism 170 for
the front door 90a will be described. The lock mechanism 170 for
the front door 90a includes a catch unit that holds the front door
90a on the apparatus body 2. The catch unit includes a first catch
portion 171 provided on the front door 90a, and a second catch
portion 172 provided on the apparatus body 2. Specifically, in the
present embodiment, the second catch portion 172 is a magnet catch
178 provided on the apparatus body 2; the first catch portion 171
includes a sticking metal plate 173, which is a held member held by
the magnet catch 178. That is, the first catch portion 171 is
provided on the front door 90a that serves as a movable unit, and
the second catch portion 172 is provided on the apparatus body 2.
The first catch portion 171 is held by the second catch portion
172, and thereby the front door 90a is held by the apparatus body
2.
As shown in FIGS. 2A and 2B, the front door 90a can pivot with the
aid of a hinge portion (not shown). With this, when the sticking
metal plate 173 sticks to the magnet catch 178, the front door 90a
is positioned at a first position, at which the front door 90a is
positioned when images are formed. At the first position, the front
door 90a is in a close state. Here, the engagement portion 131a of
the locking member 131 has a thickness T in the moving direction of
the front door 90a, smaller than a width W of the gap portion 122
of the hook portion 121a of the holder 121. Thus, as shown in FIG.
6A, when the front door 90a is positioned at the first position and
the lock unit 110 is in the lock state, predetermined gaps S1 and
S2 are ensured between the holder 121 and the locking member 131 in
the moving direction of the front door 90a. More specifically, the
lock unit 110 is configured such that, while the locking member 131
pivots, the gap S1 is ensured between one side of the engagement
portion 131a and the holder 121 and the gap S2 is ensured between
the other side of the engagement portion 131a and the holder 121,
in the moving direction of the front door 90a so that the
engagement portion 131a does not rub against the holder and not
cause a malfunction.
By the way, when a user mistakenly tries to open the front door 90a
in a state where the front door 90a is locked, a side portion 131a1
of the engagement portion 131a on a side opposite to the front door
90a side contacts the hook portion 121a of the holder 121, and
locks the front door 90a so that the front door 90a is not opened.
At this time, the front door 90a is moved by a distance of the gap
S1, and positioned at a third position, at which the side portion
131a1 of the engagement portion 131a and the holder 121 contact
each other. Thus, the front door 90a is set in a half-open state.
The third position is located between the first position and a
second position at which the front door 90a is opened. That is, the
third position is an intermediate position which is between the
first position and the second position, and at which the locking
member in a lock position and the locked member contact each other.
In the half-open state, however, the sticking metal plate 173
provided on the front door 90a can be separated from the magnet
catch 178. If the sticking metal plate 173 is separated from the
magnet catch 178, the front door 90a is displaced from a desired
position, and the holder 121 and the locking member 131 can keep
contact with each other. In this state, even though the solenoid
132 is energized to release the lock state, the lock state may not
be released because the locking member 131 is prevented from
pivoting.
As countermeasures to this, the lock mechanism 170 includes a
closing mechanism that closes the front door 90a in the half-open
state, into the close state. Specifically, the first catch portion
171 includes a base 175 and a stopper 176. The base 175 supports
the sticking metal plate 173 via a guide shaft 174 such that the
sticking metal plate 173 can move in a relative manner. The stopper
176 is provided to an end portion of the guide shaft 174 on a side
opposite to the sticking metal plate 173 side. With this
configuration, the sticking metal plate 173 is supported such that
the sticking metal plate 173 can move along the guide shaft 174 in
the moving direction of the front door 90a, and is prevented by the
stopper 176 from falling off.
In addition, a spring 177 is provided between the sticking metal
plate 173 and the base 175. Thus, when the magnet catch 178 and the
sticking metal plate 173 are in contact with each other by the
magnetic force, the front door 90a is urged, by the urging force of
the spring 177, toward the direction in which the front door 90a is
substantially closed. That is, the spring 177 is arranged such
that, in the state where the sticking metal plate 173 is held by
the magnet catch 178, as the front door 90a moves toward the second
position, the spring 177 increases its urging force. In addition,
the front door 90a is positioned at the first position by the base
175 and the sticking metal plate 173 contacting each other.
When a user tried to open the locked front door 90a, the front door
90a is moved relative to the sticking metal plate 173 while the
sticking metal plate 173 sticks to the magnet catch 178. During
this, the spring 177, which is arranged between the sticking metal
plate 173 and the front door 90a, is compressed, increasing its
reaction force (i.e. urging force applied to the front door
90a).
When the engagement portion 131a of the locking member 131 contacts
the holder 121 to prevent the front door 90a from being opened any
more, and when a user moves his/her hand off the front door 90a,
the urging force of the spring 177 forces the front door 90a to
move toward the first position. Then, the sticking metal plate 173
contacts the base 175, and the front door 90a is positioned at the
first position again. The urging force of the spring 177 is set so
that the spring force can move the front door 90a, located at the
position at which the front door 90a is positioned when the locking
member 131 and the holder 121 contact each other, to the first
position in a state where no external force is applied to the front
door 90a.
When a user tries to open the front door 90a in a state where the
front door 90a is unlocked and the sticking metal plate 173 sticks
to the magnet catch 178, the sticking metal plate 173 continues to
stick to the magnet catch 178 until the spring 177 is fully
contracted and the stopper 176 contacts the base 175. At this time,
the spring 177 produces a maximum reaction force, but the maximum
reaction force is set smaller than the sticking force of the magnet
catch 178. When the user further opens the front door 90a, the
sticking metal plate 173 is separated from the magnet catch 178 and
can be released. That is, with the movement of the movable unit
from the first position toward the second position, the first catch
portion 171 is no longer held by the second catch portion 172. In
the present embodiment, the sticking force of the magnet catch 178
is set at 20 N or more, and the maximum reaction force (maximum
urging force) of the spring 177 is set at 10N or less. Preferably,
the reaction force of the spring 177 is half or less of the
sticking force of the magnet catch 178, as in the present
embodiment, in consideration of user operability and the fact that
the sticking metal plate 173 can reliably stick to the magnet catch
178.
In the present embodiment, the urging force of the spring 177 that
serves as an urging portion can automatically return the front door
90a in its half-open state (third position) to the desired position
(first position), as described above. This can prevent the lock
unit 110 from unlocking the front door 90a in the state where the
front door 90a is in the half-open state, and can pivot the locking
member 131 in the state where the gaps S1 and S2 are ensured
between the holder 121 and the locking member 131 (i.e. state where
there is less frictional force). That is, the present embodiment
allows the gaps to be ensured between the hook member 121 and the
locking member 131 by the urging force of the spring 177 moving the
front door 90a to the position at which the front door 90a is
closed. This can prevent deformation of the door member and
insufficient pivoting of the locking member caused by a user
mistakenly operating the door into the half-open state, and by the
hook member and the locking member contacting each other. With
this, the locking member 131 can smoothly pivot. Even in the case
where the locking member moves with the aid of its own weight, the
locking member 131 can smoothly pivot and the lock mechanism can
stably operate. Moreover, since the solenoid can be downsized,
power saving and cost reduction are achievable.
In the above-described embodiment, the front door 90a, which is
used to cover a front face of the apparatus body 2 and can open and
close, is the movable unit provided such that the movable unit can
move relative to the apparatus body 2. However, the movable unit
that can move between the first position, at which the movable unit
is positioned when images are formed, and the second position that
is away from the first position may be a drawing unit that can be
drawn out from the apparatus body 2. That is, the movable unit may
be a drawing unit, such as the sheet conveyance unit 100, and the
sheet conveyance unit 100 may be locked by the lock unit 110.
Alternatively, both the door member and the sheet conveyance unit
may be a movable unit that can be locked, and may be locked by the
lock unit 110.
Also in the above-described embodiment, the first lock portion 120
is constituted by the holder 121, and the second lock portion 130
is constituted by the drive unit. The present invention, however,
is not limited to this. The first lock portion 120 may be
constituted by the drive unit, and the second lock portion 130 may
be constituted by the holder. That is, the present invention is
applicable as long as one of the first and the second lock portions
is the holder 121 and the other is the drive unit.
Furthermore, in the present embodiment, since the sticking metal
plate 173, which serves as a held member, is supported such that
the sticking metal plate 173 can move relative to the movable unit,
e.g., front door 90a, the held member can be held by the second
catch portion 172 even when the movable unit moves to the third
position in a state where the movable unit is locked. That is,
since the sticking metal plate 173 can move in a relative manner,
via the guide shaft 174, in the direction in which the front door
90a is opened and closed, the sticking metal plate 173 is not
separated from the magnet catch 178 even when a user tried to open
the front door 90a in a state where the front door 90a is locked.
That is, when the front door 90a moves by a distance of the gap S1,
the sticking metal plate 173 can move in a relative manner,
following the movement of the front door 90a. In addition, the
spring 177 that serves as an urging portion is arranged between the
held member and the movable unit such that the spring 177 increases
its urging force as the movable unit moves toward the second
position. Thus, the movement of the movable unit to the third
position can also increase the urging force of the spring 177.
However, the sticking metal plate that serves as a held member may
not necessarily be provided on the movable unit side, but may be
provided on the apparatus body side. That is, the first catch
portion may be constituted by a component, such as a magnet catch
or a C-type catch; the second catch portion may be provided with a
held member that engages with the first catch portion and is
supported such that the held member can move relative to the
apparatus body. In this case, an elastic member is arranged between
the held member and the apparatus body so that the urging force of
the elastic member increases as the movable unit moves toward the
second position.
In the present embodiment, the locking member 131 can move to an
unlock position with the aid of its own weight. That is, the
locking member 131 moves, with the aid of its own weight, from a
lock position at which the locking member 131 is located in the gap
portion 122 (i.e. position at which the locking member 131 engages
with the locked member and locks the movable unit), to the unlock
position (retracting position) to which the locking member 131 is
retracted from the gap portion 122. More specifically, the weight
balance of the locking member 131 is set such that a rotation
moment of the locking member 131 in a direction in which the
locking member 131 pivots from the lock position to the unlock
position is larger than a rotation moment of the locking member 131
in a direction in which the locking member 131 pivots from the
unlock position to the lock position. With this structure, the lock
unit can be simplified in configuration, compared to another lock
unit which uses an urging member to move the locking member 131 to
the unlock position, because the lock unit of the present
embodiment has no urging member. The lock unit of the present
embodiment can also contribute to reduction in portions cost and
assembling cost. Moreover, the present embodiment is also
applicable to a case where the use of the urging portion is
difficult due to, for example, a spatial restriction, and thus can
increase versatility.
In addition, the holder 121 that serves as a hook member and the
locking member 131 are positioned in the lock state such that a
line C passing through the contact point between the hook member in
the third position and the locking member and through the pivot
supporting axis (see FIG. 3B) is substantially parallel to the
moving direction of the movable unit. Thus, a force (i.e. force
applied in a direction indicated by an arrow Z in FIG. 3B) applied
by a user who tries to open the movable unit (front door 90a) can
be received by the pivot shaft 133. Also, since the drive portion
needs not to oppose the force applied by a user who moves the
exterior cover, the drive portion can be downsized.
The above-described embodiment exemplifies the coil spring 177 that
is an elastic member and serves as an urging portion. The present
invention, however, is not limited to the coil spring, but can use
any component, such as a rubber spring or a plate spring, as long
as the component can exert its urging force on the movable unit.
Alternatively, a spring member arranged between the front door 90a
and the apparatus body 2 may be used as an urging portion.
The second catch portion 172 is constituted by the magnet catch
178. However, at least one of the held member and the second catch
portion may be a magnet. Both the held member and the second catch
portion may be a magnet. The second catch portion 172 may be
constituted by not the magnet catch, but another component, such as
a C-type catch, that causes the held member to stick to the
component by elastic force.
Moreover, in the above-described embodiment, the weight balance of
the locking member 131 itself is set such that a portion of the
locking member 131 on the solenoid side with respect to the pivot
shaft 133 weighs more than a portion of the locking member 131 on
the engagement portion side. However, the total weight of the
portion on the solenoid side and an ion core may be greater than
the weight of the portion on the engagement portion side.
The lock unit 110 is configured such that the locking member moves
into or out of the concave gap portion of the hook member. The
present invention, however, is not limited to this. For example,
the locking member may move into or out of a hole-shaped gap
portion. Alternatively, a gap portion may be formed between a main
body of the front door and the holder for example, and the locking
member may move into or out of the gap portion between the front
door and the holder. The lock unit 110 may be configured such that
a locking member is moved linearly by a solenoid to move into or
out of a gap portion of the holder. In this case, the locking
member may move into a hole-shaped gap portion when the solenoid is
turned on, and move out of the gap portion by its own weight when
the solenoid is turned off. In addition, although the present
invention is applied to laser printers in the above-described
embodiments, it is not limited to this. For example, the present
invention is also applicable to image forming apparatuses, such as
ink-jet printers, printing machines, copying machines, and
facsimiles. Also, the above-described embodiments may be combined
as appropriate.
While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is
not limited to the disclosed exemplary embodiments. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all such modifications and equivalent structures
and functions.
This application claims the benefit of Japanese Patent Application
No. 2016-137495, filed Jul. 12, 2016, which is hereby incorporated
by reference wherein in its entirety.
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